Colds
Main feature: watery to mucoid, sometimes purulent nasal discharge "coryza".
Often preceded by a sore throat, sometimes accompanied by fever and often
followed by transient opportunist bacterial infection.

Pharyngitis ("sore throat")
Generalised erythema of pharynx, not localised to the tonsils and not associated
with coryza. Some fever present.

Tonsillitis
Local infection of tonsils = red, swollen with exudate on the surface. (Bacterial
tonsillitis
is quite common.)

Sinusitis & Otitis Media
Painful inflammatory conditions of sinuses and middle ear. Drainage of these
spaces may be impaired and lead to bacterial infection. (Bacterial infections
are usually secondary to viral infection of the nose and pharynx.)

Influenza
Fever, myalgia, sore throat, headache, prostration - usually NOT much nasal
discharge compared to a cold. Maybe some cough.

Acute BronchiolitisInflammation of terminal bronchioles in small children.
Bronchiole diameter is larger during inspiration than during expiration
and this leads to hyperinflation of air sacs distal to bronchiole.
Complete plugging of bronchiole with air resorption leads to collapse.
These features can be seen on x-ray. Usually preceded by
coryzal symptoms which later develops into the major pulmonary illness.
Clinically there is fever, rapid respiration, exhausting cough and wheezing.

Pneumonia & BronchopneumoniaAcute respiratory disease accompanied by fever, restlessness and
cyanosis (blue discolouration of skin due to low oxygen). Often not much clinical "consolidation". Again, can
be life-threatening.

TuberculosisTB, or tuberculosis, is a disease caused by bacteria called
Mycobacterium tuberculosis. The bacteria can attack any part of your body,
but they usually attack the lungs. TB disease was once the leading cause
of death in the United States.